THE CONDUCTIVITY BALANCE 489 



of conductivity, followed, after long-continued action, by 

 depression. 



These facts are illustrated in an extremely interesting 

 manner in the records given in figs. 297 and 298. In both 

 these cases the solution was applied on the right arm of the 

 balance at C, the difference being only that in the first experi- 

 ment the strength of solution was '5, and in the second 2 per 

 cent. An inspection of fig. 297 shows that the application 

 of the first induced a great and immediate enhancement of 

 conductivity, causing resultant up-responses, which were par- 

 ticularly marked during the first four minutes. This increased 



FIG. 298. Photographic Record of Effect of Stronger Dose (2 per cent.) 

 of Na 2 CO s Solution on Conductivity. 



The solution was applied on the right arm of the balance C. Note grow- 

 ing depression and appearance of diphasic effect. 



conductivity is then seen to undergo a continuous decrease 

 and reversal into growing depression, as seen in the substi- 

 tution of increasing down-responses. This record deserves 

 special attention, inasmuch as it affords us an insight into a 

 phenomenon which could not otherwise have been suspected. 

 Greater conductivity is usually associated with increased 

 velocity of transmission. It would appear, however, that the 

 term conductivity really covers two different phenomena 

 which may not always be concomitant. That is to say, 

 an increase of conductivity may mean either a greater speed 

 of transmission of excitation or a greater intensity of the 



